This invention relates to electrical wiring boxes. More particularly, it is concerned with electrical wiring box arrangements having integral cable clamps.
Many known types of electrical wiring box and cable clamp arrangements are of a type wherein the cable clamp and wiring box are separate and must be assembled, either at the time the box is manufactured, or later when the box is wired. One such type of box and clamp, of the type disclosed in U.S. Pat. No. 3,424,856, for example, requires that the cable be inserted in the clamp before the clamp is installed in a knock-out opening of the wiring box. The cable is clamped simultaneously with the installation of the clamp device in the knock-out aperture. Wiring box and clamp arrangements of this type do not allow for removal or repositioning of the cable in the clamp without removal of the clamp from the knock-out opening.
Yoke type cable clamps of the type disclosed in U.S. Pat. No. 2,973,212 clamp the cable between a wall of the box and a cable gripping yoke driven against the cable by means of a screw or bolt. This type of clamp involves additional cost of manufacture, owing to the need for threaded openings in the box wall, and to its several parts. Moreover, the installation of a cable in boxes fitted with such clamp devices in the field requires the time consuming step of tightening the clamp holding screw or bolt.
Cable clamp devices which make use of spring-loaded cable gripping elements have been disclosed. U.S. Pat. No. 2,556,977, for example, discloses one such clamp device which comprises a right angle mounting element and spring loaded foot. The cable is gripped between one leg of the right angle element and the spring foot. The short length of the spring loaded cable gripping foot in such clamps restricts them for use with a limited range of cable diameters.
It is therefore an object of this invention to provide improved wiring box and cable clamp arrangements which overcome the aforementioned disadvantages.
It is a further object of this invention to provide a cable clamp device which is integral with an electrical wiring box, thus saving manufacturing cost and field installation time.
It is a still further object of this invention to provide an electrical wiring box and cable clamp arrangement which is capable of use with wiring cables of a variety of sizes.
Another object of this invention is to provide a cable clamp and electrical wiring box arrangement which allows for ease of installation and clamping of an electrical cable while permitting simple repositioning or removal of the cable if required.